Monitoring the level of serum paraoxonase 1 activity in liver transplantation patients

BACKGROUND: Paraoxonase 1(PON1) is an ester hydro- lase in serum and in the liver. Studies have suggested that PON1 measurement to the current battery of tests may im- prove the evaluation of chronic liver diseases. The aim of this study was to investigate the clinical significance of mo- nitoring the level of serum PON1 activity in liver transplan- tation patients. METHODS: A series of biochemical indexes were moni- tored in preoperative, operative and postoperative serum samples of 17 liver-transplanted patients. The change of se- rum PON1 level and its relations with other biochemical in- dexes were analyzed. RESULTS: PON1 was distributed normally in the healthy population and its reference value ranged from 45.5 to 265.8 U/mL. The PON1 level of all patients was lower than that of control group significantly (P<0.001); the level be- gan to elevate continuously 5 minutes after opening of the portal vein and was higher than that 90 minutes after open- ing of the portal vein ( P <0.05). Two days after operation it was still higher than the normal. The levels of serum ALT and AST elevated more significantly after opening of the portal vein than before operation and they were higher than the normal values till 2 days after the operation. CONCLUSIONS: The level of PON1 in serum may be taken as one of the effective indexes to assess whether the implant is alive and to monitor liver function of the patient together with other tests.

Analysis of Single Nucleotide Polymorphism in Human Paraoxonase 1 Gene(Q192R) with Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

Introduction Single nucleotide polymorphisms （SNPs） are the most abundant DNA markers in the human genome occurring at a frequency of one in every 500--1000 nucleotides. A variety of methods have been used for the analysis of single nucleotide polymorphisms, including restriction fragment length polymorphism （RFLP）, direct sequencing by using laser-induced fluorescence detectionTM, fluorescence energy transfer, MALDI-TOF MS combined with primer extension or invasive cleavage, and fluorescence polarization. During the past two decades, mass spectrometry has become a very popular tool in the analysis of biomolecules and is perfectly suited to the analysis of single nucleotide polymorphisms （SNPs） due to its speed, low cost, and accuracy. In this work, we used MALDI TOF mass spectrometry to detect the fragments of restriction endonuclease hydrolysis of PCR products flanking a SNP located at paraoxonase 1（Q192R）. Compared with electrophoresis, this method requires less time of analysis and possess a higher accuracy.

Pros and Cons in Therapeutic Evaluation of Paraoxonase 1 in Nerve Agent Toxicity

PON 1 （Paraoxonase 1） has been proposed as an efficient catalytic bioscavenger to combat against OP （organophosphate） and CWNA （chemical warfare nerve agent） toxicity. Unlike stoichiometric bioscavengers such as butyrylcholinesterase, catalytic bioscavengers are cost effective with the advantage of eliminating all the OPs/CWNAs at low doses. Analysis of catalytic bioscavenger efficacy of PONI showed promising results by various group of researchers. Still, there are large numbers of grey areas which are not addressed so far. One of the major areas of interest is the pharmacokinetic analysis of infused PON 1 in multiple animal models. It is shown that previous studies in mice significantly increased half-life of PONI, while recent studies in guinea pigs from our group showed reduced half-life of PON1. Similar results were reported by other research groups in guinea pigs and non-human primates. The short half-life of exogenously administered PON1 in multiple animal models may be due to poor association of PON1 with its endogenous carrier, high density lipoprotein or lower doses of PON 1 or a reflection of species difference. These observations warrant the significance of thorough pharmacokinetic analysis of infused PON 1 and the development of alternative approaches for successful utility of PON 1 as an efficient medical countermeasure against OP/CWNA toxicity.

Effect of Astragalin on Paraoxon-induced Vascular Endothelium Dysfunction

[ Objective] The paper was to explore the effect of astragalin on paraoxon-indueed vascular endothelium dysfunction and analyze the potential mecha- nism. [Method]The isolated rat thoracic aorta rings were exposed to medium contained paraoxon （3.63 μmol/L）, and astragalin （10 μmol/L） was used to inhib- it the damage effect. Rat thoracic aorta rings were suspended in organ chambers to assess vas orelaxation activity in vitro by acetyleholine （ACh）-induced endotheli- um dependent relaxation reaction （EDRR） and sodium nitroprusside （SNP）-induced endothdium-independent relaxation reaction. [Result]The exposure to parao- xon （3.63 μmol/L） resulted in an inhibition of the EDRR, markedly reduced the level of nitric oxide （NO）, the activity of paraoxonasel （PON1） and superoxide dismutase （SOD）, and significantly increased the level of malondialdehyde （MDA） in isolated rat thoracic aorta. However, the presence of astragalin （10 μmol/L） markedly attenuated the vascular endothelium dysfunction induced by paraoxon via increasing level of NO, activity of PON1 and SOD, as well as reducing level of MDA. In addition, treatment of astragalin （ 10 μmol/L） showed a similar effect to hydrogen peroxide （ 1.0 μmol/L）, a kind of antioxidant, on paraoxon- induced vascular endothelium dysfunction. [ Conclusion] Astragalin could protect the vascular endothelium against the paraoxon-induced dysfunction in isolated rat thoracic aorta, and＇the beneficial effects of astragalin might be concerned with the antioxidation of astragalin due to inhibiting the decreased activity of PONI.

Gln192Arg polymorphism in paraoxonase 1 gene is associated with Alzheimer disease in a Chinese Han ethnic population

Background Oxidative stress such as low-density lipoprotein （LDL） oxidation is thought to be an important mechanism in Alzheimer＇s disease （AD）. Paraoxonase 1 （PON1）, an enzyme located on high-density lipoprotein, can prevent LDL from oxidation to some extent. It is also a potent cholinesterase inhibitor and an arylesterase, combating organophosphate poisoning and metabolization of environmental neurotoxins which might be responsible for neurodegeneration with aging.We evaluated the association of Gln192Arg polymorphism in the PON1 gene with AD in a Chinese Han ethnic population. Methods Patients and age-matched controls were recruited from outpatient clinics and a population-based epidemiological survey, respectively. Gln192Arg polymorphism in the PON1 gene was detected by allele-specific PCR technique in 521 patients with AD and 578 healthy controls. Results The presence of at least one of PON1 R alleles （Q/R or R/R） was lower in AD patients than in the controls （82.7% vs 87.4%; χ^2 = 4.68, P = 0.03）. PON1 gene R allele frequency was lower in AD patients than in the controls （60.7% vs 64.7%; χ^2=3.85, P = 0.05）. One-way ANOVA showed that PON1 genotype had no effect on the age of onset for developing AD. Logistic regression analysis demonstrated the age and sex-adjusted odds ratio （OR） for the risk of AD in PON1 of PON1 R allele carriers was 0.71 （P = 0.044, 95%CI, 0.51 - 0.99）.Conclusion Our results indicate that Gln192Arg polymorphism in the PON1 gene is associated with AD, and PON1 R allele might be a protective factor for AD in a Chinese Han ethnic population.

Novel neuroprotective and hepatoprorective effects of citric acid in acute malathion intoxication

Objective: To study the effect of citric acid given alone or combined with atropine on brain oxidative stress, neuronal injury, liver damage, and DNA damage of peripheral blood lymphocytes induced in the rat by acute malathion exposure. Methods: Rats were received intraperitoneal(i.p.) injection of malathion 150 mg/kg along with citric acid(200 or 400 mg/kg, orally), atropine(1 mg/kg, i.p.) or citric acid 200 mg/kg+atropine 1 mg/kg and euthanized 4 h later. Results: Malathion resulted in increased lipid peroxidation(malondialdehyde) and nitric oxide concentrations accompanied with a decrease in brain reduced glutathione, glutathione peroxidase(GPx) activity, total antioxidant capacity(TAC) and glucose concentrations. Paraoxonase-1, acetylcholinesterase(ACh E) and butyrylcholinesterase activities decreased in brain as well. Liver aspartate aminotransferase and alanine aminotransferase activities were raised. The Comet assay showed increased DNA damage of peripheral blood lymphocytes. Histological damage and increased expression of inducible nitric oxide synthase(i NOS) were observed in brain and liver. Citric acid resulted in decreased brain lipid peroxidation and nitric oxide. Meanwhile, glutathione, GPx activity, TAC capacity and brain glucose level increased. Brain ACh E increased but PON1 and butyrylcholinesterase activities decreased by citric acid. Liver enzymes, the percentage of damaged blood lymphocytes, histopathological alterations and i NOS expression in brain and liver was decreased by citric acid. Meanwhile, rats treated with atropine showed decreased brain MDA, nitrite but increased GPx activity, TAC, ACh E and glucose. The drug also decreased DNA damage of peripheral blood lymphocytes, histopathological alterations and i NOS expression in brain and liver. Conclusions: The study demonstrates a beneficial effect for citric acid upon brain oxidative stress, neuronal injury, liver and DNA damage due to acute malathion exposure.

Connecting inorganic mercury and lead measurements in blood to dietary sources of exposure that may impact child development

Pre-natal and post-natal chemical exposures and co-exposures from a variety of sources including contaminated air,water,soil,and food are common and associated with poorer birth and child health outcomes.Poor diet is a contributing factor in the development of child behavioral disorders.Child behavior and learning can be adversely impacted when gene expression is altered by dietary transcription factors such as zinc insufficiency or deficiency or by exposure to toxic substances permitted in our food supply such as mercury,lead,or organophosphate pesticide residue.Children with autism spectrum disorder and attention deficit hyperactivity disorders exhibit decreased or impaired PON1 gene activity which is needed by the body to metabolize and excrete neurotoxic organophosphate pesticides.In this current review we present an updated macroepigenetic model that explains how dietary inorganic mercury and lead exposures from unhealthy diet may lead to elevated blood mercury and/or lead levels and the development of symptoms associated with the autism and attention deficithyperactivity disorders.PON1 gene activity may be suppressed by inadequate dietary calcium,selenium,and fatty acid intake or exposures to lead or mercury.The model may assist clinicians in diagnosing and treating the symptoms associated with these childhood neurodevelopmental disorders.Recommendations for future research are provided based on the updated model and review of recently published literature.

缺血性脑卒中患者半胱氨酸与PON-1 Q192R基因多态性的研究

目的探讨缺血性脑卒中患者同型半胱氨酸(Hcy)与PON-1 Q192R基因多态性的相关性。方法采用循环酶联免疫法检测血浆Hcy浓度以及使用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)方法检测140例缺血性脑卒中患者(病例组)和117名健康者(对照组)PON-1 Q192R基因多态性。结果病例组和对照组平均空腹血浆Hcy浓度分别为(14.02±4.94)μmol/L和(11.64±4.18)μmol/L,两组差异有统计学意义(t=4.09,P<0.001);将病例组和对照组作为一个研究整体发现:PON-1QQ型、QR型、RR型的平均空腹血浆Hcy浓度分别是(13.34±3.91)μmol/L、(13.14±4.98)μmol/L、(13.30±4.31)μmol/L,经方差分析,PON-1各基因型间血浆Hcy浓度差异无统计学意义(F=0.033,P=0.967)。结论血浆Hcy浓度升高与缺血性卒中有关,并且缺血性脑卒中患者Hcy与PON-1 Q192R基因多态性无关。